Given the morphological characteristics in association with the fact that the imunohistochemical profile of pleomorphic LCIS is more likely oestrogen receptor-negative and HER-2-positive along with a higher Ki-67 proliferation index that classic LCIS, these lesions have been correlated with a more aggressive biological behavior than that of classic LCIS; however, epidemiological studies to prove this assumption are lacking[1,10]. The gene discussed is MKI67; the disease is lobular breast carcinoma in situ.